Method of manufacturing a spin-valve giant magnetoresistive head

ABSTRACT

Multiple thin films of spin-valve GMR sensor are formed in a trapezoidal cross-sectional shape by laminating an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic conductive layer, a free magnetic layer and a nonmagnetic protective layer on a lower insulated gap layer. The amount of etching of the lower insulated gap layer produced in the process of patterning the spin-valve giant magnetoresistive layers into the multiple thin films of spin-valve GMR sensor is 10 nm or less. Further, the angle θ which the tangent line of each side face of the multiple thin films to the middle line of the free magnetic layer in its thickness direction forms with respect to the middle line of the free magnetic layer becomes 45 degrees or more. This structure makes it possible to provide such a spin-valve giant magnetoresistive head that it meets the requirements for securing constant breakdown voltage and preventing instability of MR output voltage waveform.

CROSS REFERENCE TO RELATED APPLICATION

This is a divisional of U.S. application Ser. No. 10/778,079, filed Feb.17, 2004, which is a divisional of U.S. application Ser. No. 09/931,255,filed Aug. 17, 2001 (now U.S. Pat. No. 6,717,778). This applicationrelates to and claims priority from Japanese Patent Application No.2000-365771, filed on Nov. 28, 2000. The entirety of the contents andsubject matter of all of the above is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a spin-valve giant magnetoresistivehead for reproducing magnetic information written in a minute singledomain on a magnetic recording medium in a magnetic recording apparatusfor use in a computer, an information processing apparatus and the like.In particular, the present invention relates to a spin-valve giantmagnetoresistive head and its manufacturing method suitably used toprevent instability of magnetoresistive (MR) output voltage waveformcaused by Barkhausen noise and obtain adequate MR output voltage,especially in a narrow-track head necessary to achieve high-densitymagnetic recording.

2. Description of the Related Art

A thin-film magnetic head for writing and reading magnetic informationis a key device to a magnetic recording apparatus. The thin-filmmagnetic head consists of a inductive write head for writing magneticinformation and a read head for reading out the magnetic informationwritten in a recording medium.

The read head for reading out the magnetic information from therecording medium includes a magnetoresistive element showing aresistance change to a very weak magnetic field applied from theoutside, or a giant magnetoresistive element showing a resistance changelarger than that of the magnetoresistive element. The reproducing headalso includes a conductive film for supplying sensing current for use insensing the resistance change.

The spin-valve giant magnetoresistive head that shows a large MR ratioto an applied magnetic field to produce a resistance change to a veryweak magnetic field includes multiple thin films of giantmagnetoresistive (GMR) sensor. The multiple thin films of GMR sensor arecomposed of at least an antiferromagnetic layer, a pinned magneticlayer, a free magnetic layer, a nonmagnetic conductive spacer thatachieves magnetic insulation between the pinned magnetic layer and thefree magnetic layer, and a nonmagnetic protective layer. The spin-valvegiant magnetoresistive head also includes magnetic-domain control layersthat maintain the magnetic orientation of the free magnetic layer insuch a state that it intersects at right angles to that of the pinnedmagnetic layer. Further, the spin-valve giant magnetoresistive includesa conductive layer that supplies sensing current to the multiple thinfilms of GMR sensor to sense the resistance change.

In the spin-valve giant magnetoresistive head, a magnetic fieldnecessary for magnetic-domain control is applied to the free magneticlayer to make a single domain of the free magnetic. This technique isimportant for preventing instability of MR output voltage waveformcaused by Barkhausen noise.

FIG. 11 shows an exemplary cross-sectional structure of a conventionalspin-valve giant magnetoresistive head as seen from the side opposite tomagnetic recording media. First, a lower magnetic shield layer 41 isformed, and a lower insulated gap layer 42 is formed on the lowermagnetic shield layer 41. Then, on the lower insulated gap layer 42,multiple thin films of GMR sensor D2 are formed in a trapezoidalcross-sectional shape. The multiple thin films of GMR sensor D2 arecomposed of an antiferromagnetic layer 1, a pinned magnetic layer 2formed on the border of the antiferromagnetic layer so that its magneticorientation can be aligned in a fixed direction, a free magnetic layer4, a nonmagnetic conductive spacer 3 that achieves magnetic insulationbetween the pinned magnetic layer 2 and the free magnetic layer 4, and anonmagnetic protective layer 5.

Magnetic-domain control layers 9 are formed on the side inclined partsof the multiple thin films of GMR sensor D2 and the lower insulated gaplayer 42. The magnetic-domain control layers 9 make the magneticorientation of the free magnetic layer 4 aligned in such a directionthat it intersects at right angles to the magnetic orientation of thepinned magnetic layer 2. Base material layers 8 for the respectivemagnetic-domain control layers 9 are formed under the magnetic-domaincontrol layers 9. Conductive layers 11 for supplying sensing current tothe multiple thin films of GMR sensor to sense a magnetic resistancechange are formed above the magnetic-domain control layers 9 throughbase material layers 10 for the respective conductive layers 11. Anupper insulated gap layer 47 and an upper magnetic shield layer 48 areformed over the multiple thin films of GMR sensor D2 and the conductivelayers 11.

In such a spin-valve giant magnetoresistive head, a magnetic fieldenough for magnetic-domain control is applied to the free magnetic layer4, which makes it possible to prevent generation of Barkhausen noise,and hence instability of MR output voltage waveform. Thus a stable headcan be provided.

One approach to reducing Barkhausen noise to prevent instability of MRoutput voltage waveform is described, for example, in JP-A-2000-215424.This publication presents such a structure that a flat part of ahard-bias layer having larger thickness than that of a free magneticlayer is positioned in the thickness direction of the free magneticlayer at the same level as the free magnetic layer. The free magneticlayer corresponds to the above-mentioned free magnetic layer 4. Thegeneration of instable MR output, however, cannot be prevented by thisapproach alone.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a spin-valve giantmagnetoresistive head and its manufacturing method capable ofrestraining instability of MR output voltage waveform.

To prevent generation of an instable MR output voltage waveform in aspin-valve giant magnetoresistive head, we directed our attention to theinclined angles of end parts of the free magnetic layer of end parts ofmultiple thin films of GMR sensor. We created spin-valve giantmagnetoresistive heads with varied and inclined angles of end parts ofthe free magnetic layer of GMR sensor and measured the probability ofoccurrence of an instable MR output voltage waveform. Experimentally, itbecomes apparent from the results of the measurement that variations ininclined angles of the end parts of the free magnetic layer of GMRsensor vary the probability of instability of MR output waveform causedby Barkhausen noise. It was found that the end parts of the multiplethin films of GMR sensor should be so made that the angle which thetangent line of each end inclined part to the middle line of the freemagnetic layer in its thickness direction forms with respect to themiddle line of the free magnetic layer is 45 degrees or more.

It is true that the tangent line of each inclined end part of themultiple thin films of GMR sensor to the middle line of the freemagnetic layer in its thickness direction should form an angle of 45degrees or more with respect to the middle line of the free magneticlayer, regardless of whether the antiferromagnetic layer in the giantmagnetoresistive thin films is of one-layer or two-layer structure.

To make the inclined angles of the end parts of the free magnetic layerof the multiple thin films of GMR sensor form an angle of 45 degrees ormore, after giant magnetoresistive thin films are formed, over etchingis conducted onto the giant magnetoresistive thin films by ion millingor the like using a mask pattern such as a resist mask pattern. Thus theinclined end parts can form an angle of 45 degrees or more. The term“over etching” denotes an etching process that takes a longer time thanthat required for etching of the above-mentioned giant magnetoresistivethin films. In this case, however, the lower magnetic gap film formedunder the giant magnetoresistive thin films is also etched in this overetching process, the thickness of portions of the lower magnetic gapfilm directly under the openings of the photoresist mask pattern isreduced. The lower magnetic gap film is a nonmagnetic insulated filmmade of Al₂O₃ or SiO₂ or both. As this film becomes thin, breakdownvoltage between the film such as the magnetic-domain control layer orthe conductive layer and the lower shield layer is made small, whichruns the danger of reducing the performance of the magnetic head.

Experiments on this point revealed that the amount of reduction in thethickness of the portion between the magnetic-domain control layer andthe lower shield layer relative to the thickness of the lower insulatedgap film directly under the giant magnetoresistive thin films should be10 nm maximum. In other words, the difference between the thickness ofthe portions of the lower insulated gap layer directly under the giantmagnetoresistive thin films and the thickness of the lower insulated gaplayer sandwiched between the magnetic-domain control layer and the lowershield layer should be 10 nm or less. This means that the amount of overetching in the process of forming the multiple thin films of GMR sensorshould be 10 nm or less.

In the process of creating such multiple thin films of GMR sensor, itwas also found that the thickness of the photoresist pattern as a maskmaterial for the etching has a great effect on the complete shape. As aresult, it became apparent that it would be better if the photoresistpattern is formed by laminating a 0.01 to 0.05 μm thick organic film anda 0.1 to 0.35 μm thick resist film.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-sectional structure of a spin-valve giantmagnetoresistive head according to a first embodiment of the presentinvention, as seen from the side opposite to recording media;

FIG. 2 is a cross-sectional view illustrating the process of forming aresist mask pattern in the manufacture of spin-valve giantmagnetoresistive heads as shown in FIGS. 1 and 18;

FIG. 3 is a cross-sectional view illustrating the process of forming aresist mask pattern in the manufacture of the spin-valve giantmagnetoresistive heads as shown in FIGS. 1 and 18;

FIG. 4 is a cross-sectional view illustrating the process of forming aresist mask pattern in the manufacture of the spin-valve giantmagnetoresistive heads as shown in FIGS. 1 and 18;

FIG. 5 is a cross-sectional view illustrating the process of forming aresist mask pattern in the manufacture of the spin-valve giantmagnetoresistive heads as shown in FIGS. 1 and 18;

FIG. 6 is a cross-sectional view illustrating the process of patterninggiant magnetoresistive thin films into a laminated body in themanufacture of the spin-valve giant magnetoresistive heads as shown inFIGS. 1 and 18;

FIG. 7 is a cross-sectional view illustrating the process of formingmagnetic-domain control layers and conductive layers in the manufactureof the spin-valve giant magnetoresistive heads as shown in FIGS. 1 and18;

FIG. 8 is a cross-sectional view illustrating the process of patterninggiant magnetoresistive thin films into a laminated body in themanufacture of a conventional spin-valve giant magnetoresistive heads asshown in FIG. 11;

FIG. 9 is a cross-sectional view for explaining the process ofmanufacturing the spin-valve giant magnetoresistive head according tothe present invention;

FIG. 10 is a cross-sectional view for explaining the process ofmanufacturing the spin-valve giant magnetoresistive head according toanother embodiment of the present invention;

FIG. 11 shows a cross-sectional structure of the conventional spin-valvegiant magnetoresistive head as seen from the side opposite to therecording media;

FIGS. 12A and 12B conceptual diagrams for explaining the principle ofthe present invention;

FIG. 13 is a graph showing a relationship between the amount of overmilling and the angle which the tangent line of each side face of thelaminated body to the middle of a free magnetic layer in its thicknessdirection forms with respect to the middle line of the free magneticlayer in the conventional manufacturing process;

FIG. 14 is a graph showing a relationship between the angle which thetangent line of each side face of the laminated body to the middle lineof the free magnetic layer in its thickness direction forms with respectto the middle line of the free magnetic layer, and the Barkhausen noisedefect rate according to the embodiment of the present invention;

FIG. 15 is a graph showing a relationship between the residual filmthickness of a lower insulated gap layer and the breakdown voltageaccording to the embodiment of the present invention;

FIG. 16 is a graph showing a relationship among the thickness of aresist film, the angle which the tangent line of each side face of thelaminated body to the middle line of the free magnetic layer in itsthickness direction forms with respect to the middle line of the freemagnetic layer, and the amount of milling width λ in a curved taper partof each side face of the laminated body according to the embodiment ofthe present invention;

FIG. 17 is an exemplary scanning-electron microscopic photograph of adual spin-valve giant magnetoresistive head according to a secondpreferred embodiment of the present invention, as seen from the sideopposite to the recording media; and

FIG. 18 shows the cross-sectional structure of the dual spin-valve giantmagnetoresistive head according to the present invention, as seen fromthe side opposite to the recording media.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Description will be made below about spin-valve giant magnetoresistiveheads according to preferred embodiments of the present invention withreference to the accompanying drawings.

First Embodiment

FIG. 1 shows the cross-sectional structure of a spin-valve giantmagnetoresistive head according to the first embodiment of the presentinvention, as seen from the side opposite to recording media. As shown,an insulated protective layer is formed on a substrate made of ceramicor the like. A lower magnetic shield layer 6 is formed on the insulatedprotective layer. A lower insulated gap layer 7 that is a nonmagneticfilm made of Al₂O₃ or SiO₂ or both is formed on the lower magneticshield layer 6. An antiferromagnetic layer 1 made of PtMn and the likeis formed on the lower insulated gap layer 7. The antiferromagneticlayer 1 is not of one-layer structure; it can be formed together with abase material layer made of Ta and the like in a multiple-layerstructure. A pinned magnetic layer 2 made of NiFe and the like is formedon the border of the antiferromagnetic layer 1 so that its magneticorientation can be aligned in a fixed direction. A free magnetic layer 4made of NiFe and the like, and a nonmagnetic conductive spacer 3 whichis made of Cu and the like to achieve magnetic insulation between thepinned magnetic layer 2 and the free magnetic layer 4 are formed abovethe antiferromagnetic layer 1. A nonmagnetic protective layer 5 isformed as the uppermost layer. Thus giant magnetoresistive thin filmsare formed.

The giant magnetoresistive thin films are patterned by etching such asion milling method using a photoresist pattern as a mask pattern intomultiple thin films of GMR sensor D1 to define the width of areproducing track. The etching process can be controlled by an end pointdetector equipment, as is known in the art. Above the side inclinedparts of the multiple thin films of GMR sensor D1 and the lowerinsulated gap layer 7, magnetic-domain control layers 9, base materiallayers 8 for the respective magnetic-domain control layers 9, conductivelayers 11 and base material layers 10 for the respective conductivelayers 11 are formed. The magnetic-domain control layers 9 is to alignthe magnetic orientation of the free magnetic layer 4 in such adirection that it intersects at right angles to the magnetic orientationof the pinned magnetic layer 2. The conductive layers 11 is to supplysensing current to the pinned magnetic layer 2, the nonmagneticconductive layer 3 and the free magnetic layer 4 to sense a giantmagnetic resistance change. An upper insulated gap layer 12 and an uppermagnetic shield layer 13 are formed over the multiple thin films of GMRsensor D1 and the conductive layers 11.

The multiple thin films of GMR sensor D1 is arranged opposite to amagnetic recording medium to sense a very weak magnetic field from aminute single domain of the magnetic recording medium. In FIG. 1, thewidth of the middle line of the free magnetic layer 4 corresponds to theread track width Twr. A difference between the maximum thickness and theminimum thickness of the lower insulated gap layer 7 corresponds to theamount of over etching OE. The horizontal width of each side face of themultiple thin films of GMR sensor D1 corresponds to the milling width λof the taper part. The minimum gap Gs between the top face of the lowermagnetic shield layer 6 and the bottom face of the upper magnetic shieldlayer 13 corresponds to the read gap length. The angle which the tangentline of each side face of the multiple thin films of GMR sensor D1 tothe middle line of the free magnetic layer in its thickness directionforms with respect to the middle line of the free magnetic layer 4corresponds to the inclined angles of each end part of the free magneticlayer 4. Making the inclined angle θ of each end part of the freemagnetic layer 4 45 degrees or more means that the milling width λ ofthe taper part is necessarily equal to or less than the total thicknessof the multiple thin films of GMR sensor D1. It should be noted herethat the pinned magnetic layer may be of laminated structure through anonmagnetic intermediate layer.

FIGS. 12A and 12B are conceptual diagrams showing cross sections ofspin-valve giant magnetoresistive heads partly constituted of multiplethin films of GMR sensor 21 and a magnetic-domain control layer 54. Ifthe magnetization of the magnetic-domain control layer 54 and theproduct of the residual magnetization and the magnetic thickness arekept constant, it can be considered that the pole density that appearsin the end part contacting the free magnetic layer is proportional tothe sine of the inclined angles of the end parts of the end part of thefree magnetic layer. Therefore, it is assumed that as the inclinedangles of the end parts of the free magnetic layer becomes steeper,magnetic instability can be reduced to prevent instability of MR outputvoltage waveform caused by Barkhausen noise. From this standpoint, itcan be considered that it would be better if the inclined angles of theend parts of the free magnetic layer is steeper.

To make sure of it, the amount of over etching was experimentally variedin the process of patterning the giant magnetoresistive thin films intothe multiple thin films of GMR sensor D1 to obtain inclined angles ofthe end part of the free magnetic layer. FIG. 13 shows the results ofchecking the relationship between the amount of over etching and theinclined angles of the end parts of the free magnetic layer. It isapparent from FIG. 13 that the inclined angles of the end parts of thefree magnetic layer of GMR sensor becomes steeper as the amount of overetching increases.

From this standpoint, trial manufacture models of elements were made byvarying the amount of over etching to determine the probability ofoccurrence of an instable MR output waveform. FIG. 14 shows the resultsof the experiment. From the relationship between the Barkhausen noiseand the inclined angles of the end parts of the free magnetic layer ofGMR sensor shown in FIG. 14, it was experimentally confirmed that theBarkhausen noise defect rate is reduced as the inclined angles of theend parts of the free magnetic layer of GMR sensor becomes larger. Then,when the inclined angles of the end parts of the free magnetic layer ofGMR sensor is 45 degrees or more, the Barkhausen noise defect ratebecomes 10% or less.

Making of high BPI accompanied with the demand for high recordingdensity tends to narrow the gap between the upper and lower shieldlayers. Making the gap narrower means that the upper and lower insulatedgap layers need to be made thinner. In particular, when the giantmagnetoresistive thin films are over-etched to form the multiple thinfilms of GMR sensor, the portions directly under the magnetic-domaincontrol layers are made thinner than the initial film thickness. Thiscauses such a problem that the breakdown voltage between the lowermagnetic shield layer and the giant magnetoresistive thin films becomestoo small.

Our experiments reveled that when the gap between the upper and lowershield layers of single spin-valve type was 0.1 μm, the thickness of thelower insulated gap layer became 30 nm, when the gap between the upperand lower shield layers of dual spin-valve type was 0.12 μm, thethickness of the lower insulated gap layer became 30 nm. Therefore, thethickness of the lower insulated gap layer was set to 30 nm to determinevalues of the film thickness of the portions of the lower insulated gaplayer directly under the magnetic-domain control layers and associatedbreakdown defect rates.

FIG. 15 shows the results of checking the relationship between the filmthickness of the lower insulated gap layer and the breakdown defect ratein such condition that the lower insulated gap layer of the spin-valvegiant magnetoresistive head is 30 nm. From the experimental results, itbecame apparent that when the residual film thickness of the lowerinsulated gap layer is 20 nm or more, the breakdown defect rate stays at10% or less. To secure a breakdown defect rate of 10% for electricalreliability, the giant magnetoresistive thin films can be over-etched upto 10 nm when the initial film thickness of the lower insulated gaplayer is 30 nm.

From the above-mentioned experimental results, it was found that theoptimum spin-valve giant magnetoresistive head that meets bothrequirements of magnetic reliability for preventing instability of MRoutput voltage waveform and electrical reliability for securingbreakdown voltage has such a structure that the amount of over etchingis 10 nm or less and the inclined angles of the end parts of the freemagnetic layer of GMR sensor is 45 degrees or more. To realize such astructure of the spin-valve giant magnetoresistive head, we went back tothe principle of ion milling.

FIG. 8 shows details of the process of creating the multiple thin filmsof GMR sensor 21 by ion milling. Ion milling is a method of irradiatingan ion beam or the like to physically remove part of the multiple thinfilms of GMR sensor. In this process, the incident angle of the ion beamis not uniform, and some beam dispersion 22 occurs. For this reason,each end part of the multiple thin films of GMR sensor 21 is formed in acurved taper shape by means of a photoresist pattern 20 as a maskpattern and the dispersion angle 22 of the ion beam.

FIG. 9 shows a case where the organic film 26 and the resist film 27 aremade thinner than those shown in FIG. 8. In this case, it is consideredthat the curved taper becomes shorter because of smaller shadow area ofthe ion beam. Such a structure reduces the milling width of the taperpart as shown by the reference numeral 29 to make the inclined angles ofthe end parts of the free magnetic layer of GMR sensor of the freemagnetic layer steeper as shown by the reference numeral 30.

FIG. 16 shows the experimental results of checking the relationshipamong the resist film thickness of a mask pattern M1, the inclinedangles of the end parts of the free magnetic layer of GMR sensor, andthe milling width of the taper part in such condition that the amount ofover etching is 6 nm. From the experimental results, it was found thatwhen the thickness of the resist film was 0.35 μm, the inclined anglesof the end parts of the free magnetic layer of GMR sensor became 45degrees or more, with the milling width of the taper part kept equal toor less than the total thickness (50 nm) of the multiple thin films ofGMR sensor D1.

To manufacture the spin-value giant magnetoresistive head of FIG. 1, thelower magnetic shield layer 6 and the lower insulated gap layer 7 areformed on the substrate as shown in FIG. 2. Then, the base material film100, the antiferromagnetic layer 1, the pinned magnetic layer 2, thenonmagnetic conductive layer 3, the free magnetic layer 4 and thenonmagnetic protective layer 5 are laminated in this order. Then, the0.01 to 0.05 μm thick organic film and the 0.1 to 0.35 μm thick resistfilm 15 are formed on the nonmagnetic protective layer 5 to form themask pattern M1 in such an undercut shape that the portions directlyunder the resist film 15 intrudes 0.15 μm or less inwardly by means ofexposure and developing treatment.

At this time, the resist film 16 may have a trapezoidal cross-sectionalshape as shown in FIG. 3. As shown in FIG. 10, if a resist film 31 istrapezoidal in cross section, and the angle 32 which the resist film 31forms with respect to the vertical direction is larger than the angle ofbeam dispersion 22, the inclined angles of the end parts of the freemagnetic layer of GMR sensor becomes far steeper. In general, since theangle of beam dispersion is about three degrees, it is preferable thatthe above-mentioned angle 32 is three degrees or more.

Then, as shown in FIG. 6, the portions that are not covered with themask pattern M1 are etched by ion milling while limiting the amount ofover etching OE to 10 nm or less. Then, the etched portions arepatterned into the multiple thin films of GMR sensor with the inclinedangles of the end parts of the free magnetic layer of GMR sensor being45 degrees or more. Then, as shown in FIG. 7, the base material layers8, the magnetic-domain control layers 9, the base material layers 10 andthe conductive layers 11 are formed in this order above the uncoveredportions of the lower insulated gap layer 7 formed by patterning themultiple thin films of GMR sensor D1, the inclined end parts of themultiple thin films of GMR sensor D1 and the mask pattern M1. Afterthat, the mask pattern M1 is lift off and removed, thus obtaining thecross-sectional structure of the spin-valve giant magnetoresistive headof FIG. 1.

The resist material forming the mask pattern M1 can be a photoresistcapable of pattern formation of 0.35 μm or less thin resist film. Forexample, a resist having the property of permitting patterning with anexposure wavelength of 365 nm, 248 nm or 193 nm, or a resist having theproperty of permitting patterning with an electron beam.

The electron-beam lithography and the photolithography can also be usedin combination. For example, a resist having the property of permittingpatterning with a combination of the exposure wavelength of 365 nm andthe electron beam, or a combination of the exposure wavelength of 248 nmand the electron beam can be used.

Second Embodiment

FIG. 18 shows an exemplary cross-sectional structure of a spin-valvegiant magnetoresistive head according the second embodiment of thepresent invention, as seen from the side opposite to the recordingmedia. This embodiment differs from the first embodiment in that such aspin-valve giant magnetoresistive head as shown in FIG. 1 containsmultiple thin films of GMR sensor D3. The multiple thin films of GMRsensor D3 is made by laminating a base material layer 100, anantiferromagnetic layer 101 made of PtMn and the like, a pinned magneticlayer 102 made of NiFe and the like and formed on the border of theantiferromagnetic layer 101 so that its magnetic orientation can bealigned in a fixed direction, a nonmagnetic conductive spacer 103 whichis made of Cu and the like to achieve magnetic insulation between thepinned magnetic layer 102 and a free magnetic layer 104, the freemagnetic layer 104 made of NiFe and the like, a nonmagnetic conductivelayer 105 made of Cu and the like, a pinned magnetic layer 106 made ofNiFe and the like, an antiferromagnetic layer 107 made of PtMn and thelike, and a nonmagnetic protective layer 108 made of Ta and the like inthis order. The above-mentioned pinned magnetic layers may be ofmultiple-layer structure through respective nonmagnetic intermediatelayers. This type of multiple thin films D3 is of so-called dualspin-valve structure.

Our experiment on the dual spin-valve giant magnetoresistive headrevealed that when the gap between the upper and lower shield layers was0.12 μm, the initial thickness of the lower insulated gap layer became30 nm.

Like in the first embodiment, it is found that the optimum spin-valvegiant magnetoresistive head that meets both requirements of magneticreliability for preventing instability of MR output voltage waveform andelectrical reliability for securing breakdown voltage has such astructure that the amount of over etching OE to 10 nm or less and theend-part inclined angle of the free magnetic layer is 45 degrees ormore. The head structure as shown in FIG. 18 can also be realized in themanufacturing process using the mask pattern M1 with the resist-filmthickness being 0.35 μm or less described in the first embodiment.

FIG. 17 shows a photograph of a dual spin-valve giant magnetoresistivehead experimentally manufactured according to the manufacturing processshown in the first embodiment, the photograph taken with ascanning-electron microscopy from the air bearing surface of magneticrecording media. In this case, it was confirmed that the inclined anglesof the end parts of the free magnetic layer in the multiple thin filmsof GMR sensor were 53 and 56 degrees, and the amount of over etching OEwas 7 nm. Further, the dual spin-valve giant magnetoresistive headachieved about 5% of breakdown defect rate in such condition that theBarkhausen noise defect rate was about 5%.

Furthermore, in the embodiment, the horizontal distance DS between sucha position that the thickness of the flat part of the magnetic-domaincontrol layer becomes 99% and the end parts of the side faces in themiddle line of the free magnetic layer was 157 nm. According to theembodiment, it is preferable that the distance DS is 200 nm or less.

Third Embodiment

This embodiment is to use only a resist film 17 to form a mask patternin the manufacturing process as shown in the first and secondembodiments. The thickness of the resist film 17 is within a range ofbetween 0.1 and 0.35 μm, and the mask pattern M3 can be formed in suchan undercut shape that each lower part up to 0.05 μm in height from thebottommost face of the resist film 17 intrudes 0.05 to 0.15 μm inwardlyin depth in parallel with the substrate.

The resist material forming the mask pattern M3 can be a photoresistcapable of pattern formation of a 0.35 μm or less thin film. Forexample, a resist having the property of permitting patterning with anexposure wavelength of 365 nm, 248 nm or 193 nm, or a resist having theproperty of permitting patterning with an electron beam.

The electron-beam lithography and the photolithography can also be usedin combination. For example, a resist having the property of permittingpatterning with a combination of the exposure wavelength of 365 nm andthe electron beam, or a combination of the exposure wavelength of 248 nmand the electron beam can be used.

Fourth Embodiment

This embodiment is to use an organic film 14, an inorganic film 18 and aresist film 15 to form a mask pattern in the manufacturing process asshown in the first and second embodiments.

As shown in FIG. 5, a 0.01 to 0.05 μm thick organic film 14 is formed onthe nonmagnetic protective layer 5. Then, a 0.1 to 0.3 μm thickinorganic film 18, made of SiO₂, Al₂O₃, Si₃N₄ or the like, is formed byion spattering on the organic film 14. Then, a 0.1 to 0.35 μm thickresist film 15 is formed on the inorganic film 18. The resist film 15 ispatterned by exposure and developing treatment to form a desired resistmask pattern. Uncovered portions of the inorganic film 18 other thanthose covered with the mask pattern are etched by reactive ion etching.Portions of the organic film 14 uncovered by the etching of theinorganic film 18 are removed by plasma ashing or the like to form themask pattern in such an undercut shape that the organic film 14 directlyunder the inorganic film 18 intrudes 0.5 to 0.15 μm inwardly. Thus adesired mask pattern M4 is formed. At this time, the amount of inwardintrusion can be controlled according to how long the ashing processlasts.

The resist material forming the mask pattern M4 can be a photoresistcapable of pattern formation of a 0.35 μm or less thin resist film. Forexample, a resist having the property of permitting patterning with anexposure wavelength of 365 nm, 248 nm or 193 nm, or a resist having theproperty of permitting patterning with an electron beam.

The electron-beam lithography and the photolithography can also be usedin combination. For example, a resist having the property of permittingpatterning with a combination of the exposure wavelength of 365 nm andthe electron beam, or a combination of the exposure wavelength of 248 nmand the electron beam can be used.

As described above, according to the present invention, the amount ofetching of the lower insulated gap layer, which is produced in theprocess of patterning the multiple thin films of GMR sensor in atrapezoidal cross-sectional shape is 10 nm or less. Further, themagnetic-domain control layers and the conductive layers are formed onboth sides of the multiple thin films of GMR sensor, and the angle whichthe tangent line of each side face of the multiple thin films of GMRsensor to the middle line of the free magnetic layer in its thicknessdirection forms with respect to the middle line of the free magneticlayer is 45 degrees or more. This structure makes it possible to providesuch a spin-valve giant magnetoresistive head that it meets both therequirements of magnetic reliability and electrical reliability forsecuring constant breakdown voltage and preventing instability of MRoutput voltage waveform.

1. A method of manufacturing a spin-valve giant magnetoresistive head comprising the steps of: forming a lower shield layer above a substrate; forming a lower insulated gap layer above said lower shield layer; forming multiple thin films above said lower insulated gap layer, said multiple thin films includes an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic conductive spacer, a free magnetic layer and a nonmagnetic protective layer; forming an organic film exhibiting a thickness within the range of 0.01 to 0.05 μm above said multiple thin films; forming an inorganic film exhibiting a thickness within the range of 0.1 to 0.30 μm; forming a desired resist mask pattern with a resist film exhibiting a thickness within the range of 0.1 to 0.35 μm; etching uncovered portions of said inorganic film under said resist mask pattern to form a desired pattern of said inorganic film; using the desired pattern of said inorganic film as a mask to etch uncovered portions of said multiple thin films under openings of the desired pattern of said inorganic film to pattern said multiple thin films into multiple thin films of GMR sensor; forming magnetic-domain control layers and conductive layers at both ends of said multiple thin films of GMR sensor; and removing said resist mask pattern to lift off said magnetic-domain control layers and said conductive layers.
 2. A method of manufacturing a spin-valve giant magnetoresistive head comprising the steps of: forming a lower shield layer above a substrate; forming a lower insulated gap layer above said lower shield layer; forming multiple thin films above said lower insulated gap layer, said multiple thin films includes an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic conductive spacer, a free magnetic layer and a nonmagnetic protective layer; forming a desired resist mask pattern above said multiple thin films with a resist film exhibiting a thickness within the range of 0.1 to 0.35 μm; making said resist mask pattern in such an undercut shape that each lower part up to 0.05 μm in height from the bottommost face of said resist film intrudes 0.05 to 0.15 μm inwardly; etching uncovered portions of said multiple thin films under openings of said resist mask pattern to pattern said multiple thin films into multiple thin films of GMR sensor; forming magnetic-domain control layers and conductive layers at both ends of said multiple thin films of GMR sensor; and removing said resist mask pattern to lift off said magnetic-domain control layers and said conductive layers.
 3. The method according to claim 1, wherein said resist film has the property of permitting resist patterning using light with an exposure wavelength of 365 nm.
 4. The method according to claim 1, wherein said resist film has the property of permitting resist patterning using light with an exposure wavelength of 248 nm.
 5. The method according to claim 1, wherein said resist film has the property of permitting resist patterning using light with an exposure wavelength of 193 nm.
 6. The method according to claim 1, wherein said resist film has the property of permitting resist patterning using an electron beam.
 7. The method according to claim 1, wherein said resist film has the property of permitting resist patterning using light with an exposure wavelength of 365 nm and an electron beam in combination.
 8. The method according to claim 1, wherein said resist film has the property of permitting resist patterning using light with an exposure wavelength of 248 nm and an electron beam in combination.
 9. The method according to claim 1, wherein said resist film has the property of permitting resist patterning using light with an exposure wavelength of 365 nm, the resist mask pattern having a trapezoidal cross-sectional shape with an angle of three degrees or more which each side face of said resist film forms with respect to the vertical direction.
 10. The method according to claim 1, wherein said resist film has the property of permitting resist patterning using light with an exposure wavelength of 248 nm, the resist mask pattern having a trapezoidal cross-sectional shape with an angle of three degrees or more which each side face of said resist film forms with respect to the vertical direction.
 11. The method according to claim 1, wherein said resist film has the property of permitting resist patterning using an electron beam, the resist mask pattern having a trapezoidal cross-sectional shape with an angle of three degrees or more which each side face of said resist film forms with respect to the vertical direction.
 12. The method according to claim 1, wherein an end point detector equipment controls the amount of etching during etching of said multiple thin films.
 13. A method of manufacturing a spin-valve giant magnetoresistive head comprising the steps of: forming multiple thin films of a GMR sensor including at least a lower shield layer, a lower insulated gap layer, an antiferromagnetic layer, a pinned magnetic layer formed on a border of the antiferromagnetic layer so that a magnetic orientation thereof is aligned in a fixed direction, a free magnetic layer, and a non-magnetic conductive spacer which achieves magnetic insulation between the pinned magnetic layer and the free magnetic layer; forming at both ends of the multiple thin films of the GMR sensor, magnetic-domain control layers operative to make the magnetic orientation of the free magnetic layer uniform, and conductive layers operative to supply current to the multiple thin films of the GMR sensor; and forming above the multiple thin films of the GMR sensor, an upper insulated gap layer and an upper magnetic shield layer; wherein the antiferromagnetic layer which is part of multiple thin films of GMR sensor is formed in at least one of a one layer and a two layer structure; wherein a read gap length indicative of a distance from the top of the lower shield layer and the bottom of the upper shield layer between which the multiple thin films of the GMR sensor are sandwiched is at least one of no greater than 0.1 μm and no greater than 0.12 μm; and wherein the angle which the tangent line of each side end face of the multiple thin films of the GMR sensor to the middle line of the free magnetic layer in a thickness direction thereof forms with respect to the middle line of the free magnetic layer is at least 45 degrees. 